This power supply is based on the Analog Devices regulator . The ADP1111 is a step-up/step-down switching regulator which can operates from an low voltage of 2 V to 12 V in step-up mode and up to 30 V in step-down mode.
The ADP1111 can be programmed to operate in step-up/stepdown or inverting applications using only three external components.
The ADP1111 offer three fixed output voltages fixed outputs of 3.3 V, 5 V and 12 V but can give another value of the output voltage using an adjustable version . In step-up mode the ADP1111 can deliver 100 mA at 5 V from a 3 V input or it can deliver 200 mA at 5 V from a 12 V input in step-down mode.
Main features of the ADP1111 switching regulator are :2 V to 30 V Input Voltage Range , 72 kHz Frequency Operation , Utilizes Surface Mount Inductors , Few External Components Required , Operates in Step-Up/Step-Down or Inverting Mode ,Low Battery Detector , User Adjustable Current Limit , Internal 1 A Power Switch , Fixed or Adjustable Output Voltage .
The ADP1111 can be used in many applications like : 3 V to 5 V, 5 V to 12 V Step-Up Converters ; 9 V to 5 V, 12 V to 5 V Step-Down Converters , Laptop and Palmtop Computers , Cellular Telephones , Flash Memory , VPP Generators , Remote Controls , Peripherals and Add-On Cards , Battery Backup Supplies , Uninterruptible Supplies , Portable Instruments and many other .
The ADP1111 can be used in many other configurations for many other applications ( see the datasheet ) but the circuit presented in this schematic simple 20 V to 5 V Step-Down Converter .